Vehicle system and method for activating hazard lights during battery disconnect events

ABSTRACT

A method according to an exemplary aspect of the present disclosure includes, among other things, activating hazard lights of an electrified vehicle in response to a high voltage battery disconnect event.

TECHNICAL FIELD

This disclosure relates to a vehicle system and method for anelectrified vehicle. The vehicle system is configured to activate one ormore hazard lights of the electrified vehicle in response to highvoltage battery disconnect events.

BACKGROUND

The need to reduce fuel consumption and emissions in vehicles is wellknown. Therefore, vehicles are being developed that reduce or completelyeliminate reliance on internal combustion engines. Electrified vehiclesare one type of vehicle currently being developed for this purpose. Ingeneral, electrified vehicles differ from conventional motor vehiclesbecause they are selectively driven by one or more battery poweredelectric machines. Conventional motor vehicles, by contrast, relyexclusively on an internal combustion engine to drive the vehicle.

Electrified vehicle powertrains are typically equipped with a highvoltage battery having a plurality of battery cells that storeelectrical power for powering the electric machines and other electricloads. During certain vehicle fault conditions, the high voltage batterymay be intentionally disconnected from the vehicle's high voltageelectrical bus, thereby resulting in the loss of vehicle motive power.

SUMMARY

A method according to an exemplary aspect of the present disclosureincludes, among other things, activating hazard lights of an electrifiedvehicle in response to a high voltage battery disconnect event.

In a further non-limiting embodiment of the foregoing method, theactivating step is performed if a speed of the electrified vehicleexceeds a predefined speed threshold.

In a further non-limiting embodiment of either of the foregoing methods,the activating step is performed if a power request from an operator ofthe electrified vehicle exceeds a predefined power request threshold.

In a further non-limiting embodiment of any of the foregoing methods,the activating step is performed if a speed of the electrified vehicleexceeds a predefined speed threshold and a power request from anoperator of the electrified vehicle exceeds a predefined power requestthreshold.

In a further non-limiting embodiment of any of the foregoing methods,the high voltage battery disconnect event indicates that the electrifiedvehicle has lost motive power.

In a further non-limiting embodiment of any of the foregoing methods,the activating step includes automatically flashing the hazard lightswithout a specific request from a vehicle operator.

In a further non-limiting embodiment of any of the foregoing methods,the method includes automatically flashing the hazard lights in a firstflashing pattern in response to the high voltage battery disconnectevent and flashing the hazard lights in a second, different flashingpattern in response to a specific request from a vehicle operator.

In a further non-limiting embodiment of any of the foregoing methods,the method includes, prior to the activating step, monitoring a highvoltage battery of the electrified vehicle for fault conditions.

In a further non-limiting embodiment of any of the foregoing methods,the method includes disconnecting the high voltage battery from a highvoltage bus to cause the high voltage battery disconnect event.

In a further non-limiting embodiment of any of the foregoing methods,the activating step includes flashing the hazard lights to provide avisual warning to a vehicle nearby the electrified vehicle if one ormore additional vehicle conditions have been met in addition to the highvoltage battery disconnect event.

A vehicle system according to another exemplary aspect of the presentdisclosure includes, among other things, a high voltage battery and atleast one control module configured to monitor the high voltage batteryand command a visual warning in response to a disconnect event of thehigh voltage battery.

In a further non-limiting embodiment of the foregoing vehicle system,the at least one control module includes a first control module and asecond control module in communication with the first control module.

In a further non-limiting embodiment of either of the foregoing vehiclesystems, the first control module is configured to monitor the highvoltage battery and the second control module is configured to commandthe visual warning.

In a further non-limiting embodiment of any of the foregoing vehiclesystem, the first control module and the second control modulecommunicate over a communication link.

In a further non-limiting embodiment of any of the foregoing vehiclesystems, a hazard light is configured to provide the visual warning.

In a further non-limiting embodiment of any of the foregoing vehiclesystems, a low voltage battery is configured to power the hazard lightduring the disconnect event.

In a further non-limiting embodiment of any of the foregoing vehiclesystems, a switch is movable between an open position in which the lowvoltage battery is decoupled from the hazard light and a closed positionin which the low voltage battery is coupled to the hazard light duringthe disconnect event.

In a further non-limiting embodiment of any of the foregoing vehiclesystems, at least one contactor is configured to selectively disconnectthe high voltage battery from a high voltage load to create thedisconnect event.

The embodiments, examples and alternatives of the preceding paragraphs,the claims, or the following description and drawings, including any oftheir various aspects or respective individual features, may be takenindependently or in any combination. Features described in connectionwith one embodiment are applicable to all embodiments, unless suchfeatures are incompatible.

The various features and advantages of this disclosure will becomeapparent to those skilled in the art from the following detaileddescription. The drawings that accompany the detailed description can bebriefly described as follows.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 schematically illustrates a powertrain of an electrified vehicle.

FIG. 2 schematically illustrates a vehicle system of an electrifiedvehicle.

FIG. 3 schematically illustrates a control strategy for providing avisual warning that an electrified vehicle has lost motive power.

DETAILED DESCRIPTION

This disclosure describes a vehicle system and method for controlling anelectrified vehicle. In some embodiments, the hazard lights of theelectrified vehicle are activated in response to a high voltage batterydisconnect event. The high voltage battery disconnect event may indicatethat the electrified vehicle has lost motive power. Flashing the hazardlights provides a visual warning to drivers of nearby vehicles of such aloss of motive power. In some embodiments, the hazard lights areactivated in response to a high voltage battery disconnect event ifcertain additional vehicle conditions are met. These and other featuresare discussed in greater detail in the following paragraphs of thisdetailed description.

FIG. 1 schematically illustrates a powertrain 10 for an electrifiedvehicle 12. Although depicted as a hybrid electric vehicle (HEV), itshould be understood that the concepts described herein are not limitedto HEV's and could extend to other electrified vehicles, including, butnot limited to, plug-in hybrid electric vehicles (PHEV's), batteryelectric vehicles (BEV's) and fuel cell vehicles.

In one embodiment, the powertrain 10 is a power-split powertrain systemthat employs a first drive system and a second drive system. The firstdrive system includes a combination of an engine 14 and a generator 18(i.e., a first electric machine). The second drive system includes atleast a motor 22 (i.e., a second electric machine), the generator 18,and a battery 24. In this example, the second drive system is consideredan electric drive system of the powertrain 10. The first and seconddrive systems generate torque to drive one or more sets of vehicle drivewheels 28 of the electrified vehicle 12. Although a power-splitconfiguration is shown, this disclosure extends to any hybrid orelectric vehicle including full hybrids, parallel hybrids, serieshybrids, mild hybrids or micro hybrids.

The engine 14, which in one embodiment is an internal combustion engine,and the generator 18 may be connected through a power transfer unit 30,such as a planetary gear set. Of course, other types of power transferunits, including other gear sets and transmissions, may be used toconnect the engine 14 to the generator 18. In one non-limitingembodiment, the power transfer unit 30 is a planetary gear set thatincludes a ring gear 32, a sun gear 34, and a carrier assembly 36.

The generator 18 can be driven by the engine 14 through the powertransfer unit 30 to convert kinetic energy to electrical energy. Thegenerator 18 can alternatively function as a motor to convert electricalenergy into kinetic energy, thereby outputting torque to a shaft 38connected to the power transfer unit 30. Because the generator 18 isoperatively connected to the engine 14, the speed of the engine 14 canbe controlled by the generator 18.

The ring gear 32 of the power transfer unit 30 may be connected to ashaft 40, which is connected to vehicle drive wheels 28 through a secondpower transfer unit 44. The second power transfer unit 44 may include agear set having a plurality of gears 46. Other power transfer units mayalso be suitable. The gears 46 transfer torque from the engine 14 to adifferential 48 to ultimately provide traction to the vehicle drivewheels 28. The differential 48 may include a plurality of gears thatenable the transfer of torque to the vehicle drive wheels 28. In oneembodiment, the second power transfer unit 44 is mechanically coupled toan axle 50 through the differential 48 to distribute torque to thevehicle drive wheels 28.

The motor 22 can also be employed to drive the vehicle drive wheels 28by outputting torque to a shaft 52 that is also connected to the secondpower transfer unit 44. In one embodiment, the motor 22 and thegenerator 18 cooperate as part of a regenerative braking system in whichboth the motor 22 and the generator 18 can be employed as motors tooutput torque. For example, the motor 22 and the generator 18 can eachoutput electrical power to the battery 24.

The battery 24 is an exemplary electrified vehicle battery. The battery24 may be configured as a high voltage traction battery pack thatincludes a plurality of battery cells capable of outputting electricalpower to operate the motor 22 and the generator 18, among othercomponents. Other types of energy storage devices and/or output devicescan also be used to electrically power the electrified vehicle 12.

In one non-limiting embodiment, the electrified vehicle 12 has two basicoperating modes. The electrified vehicle 12 may operate in an ElectricVehicle (EV) mode where the motor 22 is used (generally withoutassistance from the engine 14) for vehicle propulsion, thereby depletingthe battery 24 state of charge up to its maximum allowable dischargingrate under certain driving patterns/cycles. The EV mode is an example ofa charge depleting mode of operation for the electrified vehicle 12.During EV mode, the state of charge of the battery 24 may increase insome circumstances, for example due to a period of regenerative braking.The engine 14 is generally OFF under a default EV mode but could beoperated as necessary based on a vehicle system state or as permitted bythe operator.

The electrified vehicle 12 may additionally operate in a Hybrid (HEV)mode in which the engine 14 and the motor 22 are both used for vehiclepropulsion. The HEV mode is an example of a charge sustaining mode ofoperation for the electrified vehicle 12. During the HEV mode, theelectrified vehicle 12 may reduce the motor 22 propulsion usage in orderto maintain the state of charge of the battery 24 at a constant orapproximately constant level by increasing the engine 14 propulsion. Theelectrified vehicle 12 may be operated in other operating modes inaddition to the EV and HEV modes within the scope of this disclosure.

FIG. 2 is a highly schematic depiction of a vehicle system 56 that maybe incorporated into a vehicle, such as the electrified vehicle 12 ofFIG. 1. The vehicle system 56 is adapted to activate one or more hazardlights 58 of the electrified vehicle 12 when the electrified vehicleloses motive power. Stated another way, the vehicle system 56 isdesigned to automatically provide a visual warning to drivers of nearbyvehicles, by flashing the hazard lights 58, in response to high voltagebattery disconnect events that result in the electrified vehicle losingmotive power.

In one non-limiting embodiment, the exemplary vehicle system 56 includesa high voltage battery 60, a high voltage load 62, a low voltage battery64, hazard lights 58, a first control module 66 and a second controlmodule 68. These and additional components of the vehicle system 56 aredescribed below.

The high voltage battery 60 may include a plurality of battery cells,capacitors, or other energy storage devices that are interconnectedrelative to one another to form the high voltage battery 60. The energystorage devices of the high voltage battery 60 store electrical energythat may be supplied to power various loads residing onboard anelectrified vehicle. In a non-limiting embodiment, the high voltagebattery 60 is capable of producing at least 100 volts of electricity.The high voltage battery 60 may supply this electrical power to the highvoltage load 62 for providing motive power to the electrified vehicle.In a non-limiting embodiment, the high voltage load 62 is an electricmachine such as an electric motor, a generator, or a combinedmotor/generator.

One or more contactors 72 may be employed to selectively open and closea connection between the high voltage battery 60 and the high voltageload 62. In one embodiment, the contactors 72 act as high voltage relaysfor electronically switching a supply current to the high voltage load62. For example, the contactors 72 may couple or decouple the highvoltage power generated in the high voltage battery 60 to or from thehigh voltage load 62. When in closed positions (shown in phantom lines),the contractors 72 couple the high voltage battery 60 to the highvoltage load 62 over a high voltage bus 74. Alternatively, when thecontactors 72 are in open positions, the high voltage battery 60 isdecoupled or disconnected from the high voltage load 62.

The low voltage battery 64 may supply electrical power to various lowvoltage electrical loads (e.g., lighting systems, logic circuitry, etc.)of the electrified vehicle. For example, the low voltage battery 64 maypower the hazard lights 58. In a non-limiting embodiment, the lowvoltage battery 64 is a 12V battery. The low voltage battery 64 may beselectively connected to and disconnected from the hazard lights 58using a switch 70.

The first control module 66 and the second control module 68 may be partof an overall vehicle control unit, such as a vehicle system controller(VSC) or could alternatively be stand-alone control units separate fromthe VSC. In one embodiment, the first control module 66 and the secondcontrol module 68 include executable instructions for interfacing withand commanding operation of various components of the vehicle system 56.The first control module 66 and the second control module 68 may bothinclude multiple inputs and outputs for interfacing with the variouscomponents, and may include processing units and non-transitory memoryfor executing the various control strategies and modes of the vehiclesystem 56.

In a non-limiting embodiment, the first control module 66 controlsoperation of at least the high voltage battery 60 and the contactors 72of the vehicle system 56. For example, the first control module 66 maymonitor temperatures of the battery cells of the high voltage battery60, may monitor and control the state of charge (SOC) of the highvoltage battery 60, may control charging and discharging operations ofthe battery cells of the high voltage battery 60, and may controlopening and closing of the contactors 72. These are but non-limitingexamples of the many potential functions of the first control module 66of the vehicle system 56.

In another embodiment, the second control module 68 controls operationof at least the low voltage battery 64 and the switch 70 for activatingthe hazard lights 58 of the vehicle system 56. For example, in anon-limiting embodiment, the second control module 68 may command theswitch 70 closed (shown in phantom lines) to activate the hazard lights58 using power from the low voltage battery 64. The second controlmodule 68 may include many other functions in addition to thesefunctions.

The first control module 66 and the second control module 68 maycommunicate with one another over a communication link 76. In onenon-limiting embodiment, the communication link 76 is a controller areanetwork designed to allow the first control module 66 and the secondcontrol module 68 to communicate with one another and with other controlmodules.

During certain fault conditions, such as battery cell overcharge and/orbattery cell over-discharging conditions, the first control module 66may command the contactors 72 open to disconnect the high voltagebattery 60 from the high voltage bus 74, and thus, disconnect the highvoltage battery 60 from the high voltage load 62. This is referred to asa “high voltage battery disconnect event” and results in the electrifiedvehicle losing motive power. The first control module 66 may communicatea signal over the communication link 76 to the second control module 68in response to detecting a high voltage battery disconnect event. Inresponse, the second control module 68 may command the switch 70 closedto activate the hazard lights 58. In this way, the vehicle system 56provides a visual warning to other vehicle drivers that motive power hasbeen lost.

FIG. 3, with continued reference to FIGS. 1-2, schematically illustratesan exemplary control strategy 100 for controlling the vehicle system 56.For example, the control strategy 100 can be performed to provide avisual warning to other vehicle drivers by flashing the hazard lights 58in response to high voltage battery disconnect events. The first controlmodule 66 and the second control module 68 can be programmed with one ormore algorithms adapted to execute the control strategy 100, or anyother control strategy. In one non-limiting embodiment, the controlstrategy 100 may be stored as executable instructions in non-transitorymemory of the first control module 66 and the second control module 68.

As shown in FIG. 3, the control strategy 100 begins at block 102. Atblock 104, the control strategy 100 monitors the high voltage battery 60for battery fault conditions. The battery fault conditions may include,among other conditions, battery cell overcharging and/or battery cellover-discharging conditions. The first control module 66 maycontinuously monitor the high voltage battery 60 for such faults.

Next, at block 106, the control strategy 100 determines whether abattery fault condition has been detected. If “NO,” the first controlmodule 66 continues to monitor the high voltage battery 60. If “Yes,”however, the control strategy 100 proceeds to block 108.

At block 108, the high voltage battery 60 is disconnected from the highvoltage load 62. In a non-limiting embodiment, the first control module66 commands the contactors 72 open to disconnect the high voltagebattery 60 from the high voltage load 62. Opening the contactors 72renders a high voltage battery disconnect event which causes theelectrified vehicle 12 to lose motive power.

The control strategy 100 next determines whether one or more additionalvehicle conditions exist for deciding whether to provide a visualwarning to other drivers that the electrified vehicle 12 has lost motivepower. This is schematically shown at block 110 of the control strategy100. In a first embodiment, the control strategy 100 determines if aspeed of the electrified vehicle 12 exceeds a predefined speedthreshold. The predefined speed threshold is a calibratable value thatmay be set at any vehicle speed. In a second embodiment, the controlstrategy 100 determines if a power request from the operator of theelectrified vehicle 12 exceeds a predefined power request threshold. Thepredefined power request threshold is a calibratable value that may bederived from an accelerator pedal position. In yet another embodiment,the control strategy 100 determines whether the speed of the electrifiedvehicle 12 exceeds a predefined speed threshold and whether a powerrequest exceeds a predefined power request threshold. Other vehicleconditions may also be monitored for determining whether to issue thevisual warning.

If the analysis at block 110 results in an answer of “NO,” the controlstrategy ends at block 112 and no visual warning is activated.Alternatively, if the answer to block 110 is “YES,” the control strategy100 proceeds to block 114 by activating the hazard lights 58 in order toprovide the visual warning of loss of motive power to other vehicleoperators. The first control module 66 may communicate a signal to thesecond control module 68 to activate the hazard lights 58. In responseto receiving this signal, the second control module 68 may command theswitch 70 closed to activate the hazard lights 58 by using power fromthe low voltage battery 64.

Once activated, the hazard lights 58 may flash in a predefined flashingpattern to provide the visual warning to vehicles that may be nearby theelectrified vehicle 12. In a non-limiting embodiment, the predefinedflashing pattern used to automatically indicate a loss of motive poweris a different flashing pattern than is used if the vehicle operator ofthe electrified vehicle 12 has specifically requested operation of thehazard lights 58, such as by depressing a button within the vehiclecabin of the electrified vehicle 12. For example, the predefinedflashing pattern used to automatically indicate loss of motive power mayflash the hazard lights 58 more rapidly than other flashing patterns todraw quicker attention to the electrified vehicle 12.

Although the different non-limiting embodiments are illustrated ashaving specific components or steps, the embodiments of this disclosureare not limited to those particular combinations. It is possible to usesome of the components or features from any of the non-limitingembodiments in combination with features or components from any of theother non-limiting embodiments.

It should be understood that like reference numerals identifycorresponding or similar elements throughout the several drawings. Itshould be understood that although a particular component arrangement isdisclosed and illustrated in these exemplary embodiments, otherarrangements could also benefit from the teachings of this disclosure.

The foregoing description shall be interpreted as illustrative and notin any limiting sense. A worker of ordinary skill in the art wouldunderstand that certain modifications could come within the scope ofthis disclosure. For these reasons, the following claims should bestudied to determine the true scope and content of this disclosure.

What is claimed is:
 1. A method, comprising: activating hazard lights ofan electrified vehicle in response to a high voltage battery disconnectevent.
 2. The method as recited in claim 1, wherein the activating stepis performed if a speed of the electrified vehicle exceeds a predefinedspeed threshold.
 3. The method as recited in claim 1, wherein theactivating step is performed if a power request from an operator of theelectrified vehicle exceeds a predefined power request threshold.
 4. Themethod as recited in claim 1, wherein the activating step is performedif: a speed of the electrified vehicle exceeds a predefined speedthreshold; and a power request from an operator of the electrifiedvehicle exceeds a predefined power request threshold.
 5. The method asrecited in claim 1, wherein the high voltage battery disconnect eventindicates that the electrified vehicle has lost motive power.
 6. Themethod as recited in claim 1, wherein the activating step includesautomatically flashing the hazard lights without a specific request froma vehicle operator.
 7. The method as recited in claim 1, comprising:automatically flashing the hazard lights in a first flashing pattern inresponse to the high voltage battery disconnect event; and flashing thehazard lights in a second, different flashing pattern in response to aspecific request from a vehicle operator.
 8. The method as recited inclaim 1, comprising, prior to the activating step, monitoring a highvoltage battery of the electrified vehicle for fault conditions.
 9. Themethod as recited in claim 8, comprising disconnecting the high voltagebattery from a high voltage bus to cause the high voltage batterydisconnect event.
 10. The method as recited in claim 1, wherein theactivating step includes flashing the hazard lights to provide a visualwarning to a vehicle nearby the electrified vehicle if one or moreadditional vehicle conditions have been met in addition to the highvoltage battery disconnect event.
 11. A vehicle system, comprising: ahigh voltage battery; at least one control module configured to monitorsaid high voltage battery and command a visual warning in response to adisconnect event of said high voltage battery.
 12. The vehicle system asrecited in claim 11, wherein said at least one control module includes afirst control module and a second control module in communication withsaid first control module.
 13. The vehicle system as recited in claim12, wherein said first control module is configured to monitor said highvoltage battery and said second control module is configured to commandsaid visual warning.
 14. The vehicle system as recited in claim 12,wherein said first control module and said second control modulecommunicate over a communication link.
 15. The vehicle system as recitedin claim 11, comprising a hazard light configured to provide said visualwarning.
 16. The vehicle system as recited in claim 15, comprising a lowvoltage battery configured to power said hazard light during saiddisconnect event.
 17. The vehicle system as recited in claim 16,comprising a switch that is movable between an open position in whichsaid low voltage battery is decoupled from said hazard light and aclosed position in which said low voltage battery is coupled to saidhazard light during said disconnect event.
 18. The vehicle system asrecited in claim 11, comprising at least one contactor configured toselectively disconnect said high voltage battery from a high voltageload to create said disconnect event.